In manufacturing electronic devices, a process of etching a ruthenium film made of ruthenium (Ru) may be performed. Japanese Patent Application Publication No. H8-78396 discloses a method of etching a ruthenium film by using plasma of a mixed gas containing oxygen (O2) and chlorine (Cl2).
In the method disclosed in Japanese Patent Application Publication No. H8-78396, the ruthenium film is etched by using the plasma of the mixed gas. Therefore, the etching rate of the ruthenium film increases or decreases depending on the flux or energy of ions and reactive species. Accordingly, in the method of etching the ruthenium film, it is necessary to suppress the variation in the etching rate.